Currently, memories are employed in various functional fields as key electronic components supporting an information society.
In conventional memories, SRAM, DRAM and FLASH are mainstream memories in which switching is performed in accordance with a change in charge capacity C. Moreover, various logic circuits, complicated memories, etc., are fabricated by combining such memories.
In recent years, there has been an increased demand for miniaturized and less expensive functional elements such as memories due to the spread of information terminals and the reduced cost of electronic components. In the field of non-volatile memories for information terminals, numerous memories which respond to the demand for miniaturization and cost reduction have been proposed by employing new techniques.
However, memories miniaturized to a nanoscale level are unsatisfactory in terms of charge capacity C. Therefore, in memories using a change in charge capacity C, there is a limit to the achievement of further miniaturization and high performance at the same time.
Recently, people have come to hold great expectations for techniques in which a variation of not charge capacity C but electric resistance R is utilized in switches or memories. Because electric resistance R is not restricted by charge capacity, there is no limit to memory miniaturization. Examples of functional elements using a variation of electric resistance R include variable-resistance elements in which an oxide represented by the chemical formula PrCaMnO3 (hereunder sometimes referred to as “PCMO”) is used, as disclosed in Patent Documents 1 and 2.
[Patent Document 1] U.S. Pat. No. 6,204,139
[Patent Document 2] Japanese Unexamined Patent Publication No. 2003-068983
[Non-patent Document 1] Physics Reports Vol. 346 (2001) pp. 387-531